Control of bubble size in a carbonated liquid

ABSTRACT

Cans, bottles and/or other containers used to hold a carbonated beverage can include internal features to promote and/or control bubble formation.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/908,622, titled “Control of Bubble Size in a Carbonated Liquid” andfiled Oct. 20, 2010. Application Ser. No. 12/908,622, in its entirety,is incorporated by reference herein.

BACKGROUND

The properties of bubbles produced in a carbonated liquid can affect useof that liquid for its intended purpose. For example, the properties ofbubbles produced in a carbonated beverage can impact the perceived tasteof the beverage and/or the sensation that the beverage creates in themouth of a person drinking the beverage (the “mouth feel” of thebeverage). In many circumstances, it is therefore desirable to controlthe size of bubbles that are produced in a beverage or other liquid.

SUMMARY

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key or essentialfeatures of the invention or to exhaustively list all embodiments.

Some embodiments include containers (e.g., cans, bottles) for holding acarbonated beverage. Such containers can be formed from plastic, metal,glass and/or other materials and include one or more internal featuresto promote and control bubble formation. In some embodiments, thesefeatures can include an internal partition. Such partitions can includeadditional surface features of various types (e.g., ridges or otherlinearly extending protrusions, bumps). Additional embodiments mayinclude beverage containers in which features to promote and/or controlbubble formation are formed on an interior bottom surface, on aninterior side surface, and/or in a neck region. Still other embodimentscan include a container with a bubble catcher or other structure thatmay be fixed to the container interior or allowed to float within aliquid held in the container. Yet other embodiments can include methodsfor fabricating and/or for using any of the herein-disclosed containers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A1-1I3 are partially schematic cross-sectional views of beveragecontainers, according to some embodiments, that include internalpartitions.

FIG. 2 shows a bottle having a neck section with riblets formed aroundthe entire inner circumference, according to some embodiments.

FIG. 3 shows a neck portion of a bottle having riblets according toanother embodiment.

FIG. 4A shows a bottle having interior dimples according to someembodiments.

FIG. 4B shows examples of additional dimple shapes and patternsaccording to some embodiments.

FIG. 5 shows a bottle according to some embodiments having riblets thatextend the length of the bottle interior.

FIGS. 6-11 show embodiments in which patterns of riblets are formed onthe interior surfaces of containers.

FIGS. 12A1-12E2 show beverage containers, according to some embodiments,having bubble forming structures formed in bottom portions of thecontainers.

FIGS. 13A1-13C2 show beverage containers having bubble catchingstructures according to some embodiments.

FIGS. 14A1-14D are beverage containers according to additionalembodiments.

FIGS. 15A and 15B are front and cross-sectional views, respectively, ofan end portion of an injection molding core rod according to someembodiments.

FIG. 15C is a block diagram showing steps in forming a plastic bottleaccording to some embodiments.

FIG. 16 are drawings of blow molding stretch rods according to someembodiments.

FIG. 17A shows a cross section of a preform created with a modified corerod.

FIG. 17B shows the interior bottom of a bottle stretch blow molded fromthe preform of FIG. 17A.

FIG. 17C shows an interior of a plastic bottle created using one of thestretch rods of FIG. 16.

FIGS. 17D and 17E show nucleation resulting from surface featuressimilar to those shown in FIG. 17C.

FIG. 18 is a cross-sectional view of a portion of a bottle according toanother embodiment.

FIG. 19 shows the variation in size and pressure of a bubble risinginside a liquid.

DETAILED DESCRIPTION

Changes in the amount and type of bubbles in a carbonated beverage cansignificantly affect the mouth feel of that beverage. For this and otherreasons, it is desirable to manipulate one or more properties of thebubbles produced in a beverage. Such properties can include the size ofbubbles produced, the shape of bubbles, the amount of bubbles generated,and the rate at which bubbles are released or otherwise generated.

A carbonated beverage may include a liquid beverage matrix and adissolved gas. The beverage matrix may include water, syrup, flavoringsand other dissolved or suspended material(s). The dissolved gas may be,e.g., carbon dioxide. Carbon dioxide may also be generated in situ fromaqueous carbonic acid. Upon lowering pressure (e.g., by opening a sealedbeverage container), carbonic acid is converted to carbon dioxide gas.Because carbon dioxide is poorly soluble in water, it is released intothe liquid matrix as bubbles.H₂CO₃→H₂O+CO₂Manipulation of bubble properties can depend on numerous factors. Onesuch factor is interfacial tension between the dissolved gas and theliquid matrix. Another factor is the composition of the liquid matrix.For example, bubble size can to some extent be controlled by addingsurface active agents (surfactants, emulsifiers, etc.) to a beveragematrix. In particular, the champagne industry has researched this issueand found that glycoprotein from grapes can be a controlling factor insmall bubble size.

Bubble properties can also depend on gaseous nucleation, i.e., theformation of bubbles from the gas dissolved in the beverage liquidmatrix. The process of bubble formation in a carbonated beverage isanalogous to formation of bubbles in a supersaturated solution of a gas.However, and as explained in more detail in Example 1 below, formationof bubbles in a supersaturated continuous liquid is improbable. Thus,some type of discontinuity is generally needed to form bubbles. Thesediscontinuities can be the result of, and nucleation can thus beaffected by, other ingredients dissolved or suspended in the liquidmatrix, surface properties of a bottle or other container holding thebeverage, and/or ice or other objects in the beverage. Gaseousnucleation in a carbonated beverage typically occurs on a surface thatis at least partially wettable by the beverage. This surface can be asurface of the beverage container and/or a surface (or surfaces) ofparticles or other objects that are suspended or floating in thebeverage.

The amount of bubbles that can be created in a carbonated liquid willdepend upon the gas available in the liquid, e.g., as dissolved gas oras a precursor such as carbonic acid. The amount of gas available in acarbonated liquid is proportional to the pressure inside the containerholding the liquid. When sealed, the pressure inside such a container istypically greater than atmospheric pressure. When the container isopened, the contained liquid is exposed to atmospheric pressure. Thisreduction in pressure is the driving force for the formation of bubblesand foam. The size, shape and rate of release of bubbles will dependupon various factors that can include: (a) the surface(s) on whichbubbles will nucleate, (b) viscosity of the liquid matrix of thecarbonated liquid, (c) interfacial tension between the carbonated liquidand the wall(s) of the container, and (d) temperature of the carbonatedliquid. In some cases, it may not be practical to vary factors (b) and(c), as this may require altering the chemical composition of thebeverage. Attempting to modify temperature (factor (d)) may also beimpractical. However, factor (a) can often be modified without affectingthe chemical composition of a beverage and without reliance on openingof a beverage container under unusual temperature conditions.

The size of the bubbles formed in a carbonated beverage can be affectedby the availability of bubble nucleation sites on a surface of thebeverage container and/or on other surfaces in contact with thebeverage, as well as by the surface tension of the carbonated liquid andthe equilibrium pressure inside of a bubble for a given bubble size.With regard to bubble shape, the tendency of a bubble to acquirespherical shape is based on low surface energy requirements for a sphere(i.e., a sphere has the lowest surface area/volume ratio). As a bubblerises, it must overcome the hydrostatic pressure exerted by the liquidabove it. During the course of rising, the bubble has to push the liquidsurrounding it. This tends to change the bubble shape from spherical tosomewhat elliptical. When two bubbles meet, they do so at a planesurface which again creates lowest surface area possible for the twobubbles. As the number of bubbles touching each other increases, theshape of a larger bubble formed by the joining smaller bubbles can varyaccordingly to create the lowest surface area possible for volume of thejoined bubbles. Therefore, the shape of bubbles can also be controlledby the number of bubbles coming in contact with one another. To a lesserextent, the shape of bubbles may also depend upon the location and depthat which nucleation occurs.

The mouth feel of a beverage is related to the size and number of thebubbles formed. The foaminess of a carbonated liquid is directlyproportional to the number of bubbles formed. Thus, variation infoaminess can lead to a different mouth feel. The addition of extremelysmall particles inside of a carbonated liquid can change the mouth feel.In particular, such particles can facilitate nucleation of bubblesinside the liquid, thereby increasing bubble quantity.

The rate of release of the bubbles in a carbonated beverage can beaffected by varying the pressure to which the beverage is exposed. Therate at which released bubbles reach the surface of a beverage can bemodified by creating obstacles in the path of rising bubbles. Suchobstacles can be introduced inside the liquid by introducing extraplates or edges. Such plates, edges and/or other structures can be usedto create an indirect path to the beverage surface.

The size, shape, release rate and quantity of bubbles are interrelated.These properties can be modified by modifying the design of a containerused to hold a carbonated beverage. In many cases, this involvescreating more surface area that contacts the beverage. This extrasurface area can provide added stability to rising bubbles and providemore control of, e.g., the rate of bubble release.

FIGS. 1A1-1I3 are partially schematic cross-sectional views of beveragecontainers, according to some embodiments, that include internalpartitions. The partition walls in these embodiments promote bubbleformation by, e.g., providing increased surface area for bubblenucleation. Moreover, these partition walls can also cause splashing ofbeverage within a container and thereby generate more bubbles. In manyconventional containers, most foam is generated immediately after acontainer is opened. Mechanical splashing of a beverage by a partitionwall may cause additional bubble generation, for a longer duration,after the container is opened. For example, a consumer sipping acarbonated beverage will tend to move the container from an uprightcondition so as to tilt the container and place the container opening atthe consumer's mouth. As a result of this periodic tilting movement, thepartition wall will agitate the beverage. This can promote bubblegeneration after container opening and help the beverage to remain in afoamy condition. Small appendages can be added to a partition wall tohinder the path of rising bubbles and slow the breakdown of the foam.

FIG. 1A1 is a cross-sectional side view of a sealed beverage containercan 10 a according to at least one embodiment. FIG. 1A2 is a topcross-sectional view of can 10 a taken from the location shown in FIG.1A1. Container 10 a includes a base 33 a, a side wall 31 a and a top 16a. Internal surfaces of base 33 a, side wall 31 a and top 16 a define aninternal volume 13 a into which a carbonated beverage 30 has beensealed. An outlet 11 a located in top 16 a is shown closed in FIG. 1A1,but is configured for opening by a consumer and is positioned oncontainer 10 a so as to permit draining of beverage 30 from container 10a after outlet 11 a is opened. Although the embodiments shown in FIGS.1A1-1I3 are can beverage containers, features similar to those shown anddescribed in connection with FIGS. 1A1-1I3 can also be included in othertypes of beverage containers in other embodiments (e.g., bottles,reusable or disposable cups, etc.).

A partition 12 a extends downward from the top 16 a of container 10 aand separates a passage 14 a from the remainder of a main volume 13 a.As shown in FIGS. 1A1 and 1A2, baffle 12 a is attached to portions ofthe internal surfaces of top 16 a and side wall 31 a. When base 33 a isresting on a flat surface, partition 12 a is oriented vertically.

Passage 14 a is smaller and differently shaped than the remainder ofmain volume 13 a. In order for beverage 30 within the remainder of mainvolume 13 a to exit through outlet 11 a after opening, beverage 30 mustflow around the lower end of partition 12 a and into passage 14 a.Partition 12 a can be formed from the same material used for the sidewalls of container 10 a or from some other material. In at least someembodiments, passage 14 a is the only fluid path between the remainderof main volume 13 a and outlet 11 a.

FIG. 1B1 is a cross-sectional side view of a beverage container can 10 baccording to another embodiment. FIG. 1B2 is a top cross-sectional viewof can 10 b taken from the location shown in FIG. 1B1. The top, sidewall and base of container 10 b, as well as tops, side walls and basesof other containers in FIGS. 1B1-1I3, the positioning of elements ofthose containers, the openable natures of outlets 11, and various otherfeatures of the containers shown in FIGS. 1B1-1I3 are similar tofeatures of container 10 a shown in FIGS. 1A1-1A2. For convenience,several of such features are not separately discussed in connection withFIGS. 1B1-1I3 where the similarities with features of container 10 a arereadily apparent from the drawings and where further discussion is notrequired to clearly understand the depicted embodiments. Similarly,carbonated beverage 30 is for convenience omitted from FIGS. 1B1-1I3.However, the presence of beverage 30 sealed within each of thecontainers of said figures is understood.

Partition 12 b is similar to partition 12 a of FIG. 1A1, but may notextend as far from the beverage can top as is the case with partition 12a. In order for beverage contained within a remainder of main volume 13b to exit through an outlet 11 b (shown in a closed position in FIG.1B1), that beverage must flow around the lower end of partition 12 b andinto passage 14 b. Partition 12 b can be formed from the same materialused for the side walls of container 10 b or from some other material.Partition 12 b includes numerous small surface features 15 b to promotenucleation and/or aeration by creating turbulent flow through passage 14b. Surface features 15 b can include short hair-like projections, smallbumps, pits or other surface indentations, etc., as well as combinationsof various types of surface features.

FIG. 1C1 is a cross-sectional side view of a beverage container can 10 caccording to another embodiment. FIGS. 1C2 is a top cross-sectional viewof can 10 c taken from the location shown in FIG. 1C1. Outlet 11 c,partition 12 c, main volume 13 c and surface features 15 c are similarto outlet 11 b, partition 12 b, main volume 13 b and surface features 15b of FIG. 1B1. Container 10 c of FIGS. 1C1 and 1C2 differs fromcontainer 10 b of FIGS. 1B1 and 1B2 by having surface features 15 c onboth sides of passage 14 c.

FIG. 1D1 is a cross-sectional side view of a beverage container can 10 daccording to another embodiment. FIG. 1D2 is a top cross-sectional viewof can 10 d taken from the location shown in FIG. 1D1. Outlet 11 d,partition 12 d, main volume 13 d and passage 14 d are similar to outlet11 c, partition 12 c, main volume 13 c and passage 14 c of FIG. 1C1.Container 10 d of FIGS. 1D1 and 1D2 differs from container 10 c of FIGS.1C1 and 1C2 by having surface features 15 d that are angled towardsoutlet 11 d.

FIG. 1E1 is a cross-sectional side view of a beverage container can 10 eaccording to another embodiment. FIG. 1E2 is a top cross-sectional viewof can 10 e taken from the location shown in FIG. 1E1. Can 10 e includesan outlet 11 e, partition 12 e, main volume 13 e and passage 14 esimilar to features described in connection with previous embodiments.In the embodiment of FIG. 1E1, however, can 10 e has no added surfacefeatures in passage 14 e. Moreover, can 10 e includes a top 16 e that iscurved so as to modify pressure exerted on the carbonated liquid.Although shown as an outward curve in FIG. 1E1 (i.e., top 16 e is convexon its outwardly exposed surface), top 16 e could alternatively becurved inward (i.e., have a concave exposed outer surface) or have othertypes of curvatures.

FIG. 1F1 is a cross-sectional side view of a beverage container can 10 faccording to another embodiment. FIG. 1F2 is a top cross sectional viewof can 10 f taken from the location shown in FIG. 1F1. FIG. 1F3 is aside cross-sectional view, taken from the location indicated in FIG. 1F1and omitting the outer walls of can 10 f, showing the face 20 f ofpartition 12 f inside of passage 14 f. Can 10 f is similar to can 10 bof FIG. 1B1, except that partition 12 f of can 10 f includes multiplehorizontal linear protrusions (e.g., ribs, ridges, riblets, etc.) 15 f.Linear protrusions 15 f are oriented in directions that are generallyperpendicular to a direction of primary flow through passage 14 f whenbeverage is drained from the remainder of main volume 13 f via outlet 11f. Each of linear protrusions 15 f can extend from face 20 f by a heightof, e.g., 100 nanometers (nm) to 5 millimeters (mm). Each of linearprotrusions 15 f can be uniform in length, width, height and othercharacteristics, or various of linear protrusions 15 f may differ in onone or more dimensions or other characteristics. For convenience, FIGS.1F1-1F3 only show 9 linear protrusions 15 f. However, a much largernumber of linear protrusions 15 f could be included, and those linearprotrusions could have a much closer spacing. Linear protrusions 15 fcan be arranged in a regular pattern as shown or may have an irregularvertical and/or horizontal distribution. Partition 12 f is otherwisesimilar to partition 12 b of FIG. 1B1. Outlet 11 f and main volume 13 fare similar to outlet 11 b and main volume 13 b of FIG. 1B1.

FIG. 1F4 is a view of a face 20 ff of a partition 12 ff of a can similarto can 10 f, and taken from a location similar to that from which theview of FIG. 1F3 was taken. Face 20 ff similar to face 20 f, except thateach of linear protrusions 15 f is replaced by multiple discontinuouslinear protrusions 15 ff separated by interruptions 18 ff. Each oflinear protrusions 15 ff can extend from face 20 ff by a height of,e.g., 100 nm to 5 mm. Linear protrusions 15 ff can be uniform in length,width, height and other characteristics, or various of linearprotrusions 15 ff may differ in on one or more dimensions or othercharacteristics. Interruptions 18 ff may similarly be uniform or mayvary. Linear protrusions 15 ff and interruptions 18 ff can be arrangedin a regular pattern as shown or may have an irregular vertical and/orhorizontal distribution.

FIG. 1G1 is a cross-sectional side view of a beverage container can 10 gaccording to another embodiment. FIG. 1G2 is a top cross-sectional viewof can 10 g taken from the location shown in FIG. 1G1. FIG. 1G3 is aside cross-sectional view, taken from the location indicated in FIG. 1G1and omitting the outer walls of can 10 g, showing the face 20 g ofpartition 12 g inside of passage 14 g. Can 10 g is similar to can 10 fof FIG. 1F1, except that face 20 g include vertical linear protrusions19 g. Linear protrusions 15 g are oriented in directions that aregenerally parallel to a direction of primary flow through passage 14 gwhen beverage is drained from the remainder of main volume 13 g viaoutlet 11 g. The number, size, shape, distribution, continuity and otheraspects of vertical linear protrusions 19 g can vary in ways similar tothe possible variations of horizontal linear protrusions 15 f and 15 ffdiscussed in connection with FIGS. 1F1 through 1F4.

FIG. 1H1 is a cross-sectional side view of a beverage container can 10 haccording to another embodiment. FIG. 1H2 is a top cross-sectional viewof can 10 h taken from the location shown in FIG. 1H1. FIG. 1H3 is aside cross-sectional view, taken from the location indicated in FIG. 1H1and omitting the outer walls of can 10 h, showing the face 20 h ofpartition 12 h inside of passage 14 h. Can 10 h is similar to can 10 fof FIG. 1F1 and to can 10 g of FIG. 1G1, except that face 20 h includesboth horizontal linear protrusions 15 h (oriented in directions that aregenerally perpendicular to a direction of primary flow through passage14 h) and vertical linear protrusions 19 h (oriented in directions thatare generally parallel to a direction of primary flow through passage 14h). The number, size, shape, distribution, continuity and other aspectsof linear protrusions 15 h and/or 19 h can vary in ways similar to thepossible variations discussed in connection with FIGS. 1F1 through 1G3.

FIG. 1I1 is a cross-sectional side view of a beverage container can 10 iaccording to another embodiment. FIG. 112 is a top cross-sectional viewof can 10 i taken from the location shown in FIG. 1I1. FIG. 1I3 is aside cross-sectional view, taken from the location indicated in FIG. 1I1and omitting the outer walls of can 10 i, showing the face 20 i ofpartition 12 i inside of passage 14 i. Can 10 i is similar to can 10 fof FIG. 1F1, to can 10 g of FIG. 1G1 and to can 10 h of FIG. 1H1, exceptthat face 20 i includes a first set of diagonal linear protrusions 21 i(extending from upper left to lower right in FIG. 1I3 in a first set ofdirections that are neither perpendicular nor parallel to a direction ofprimary flow through passage 14 i) and a second set of diagonal linearprotrusions 22 i (extending from upper right to lower left in FIG. 1I3in a second set of directions that are neither perpendicular norparallel to a direction of primary flow through passage 14 i). Thenumber, size, shape, distribution, continuity and other aspects oflinear protrusions 21 i and/or 22 i can vary in ways similar to thepossible variations discussed in connection with FIGS. 1F1 through 1H3.

In other embodiments, and similar to the embodiments of FIGS. 1C1through 1D2, both sides of a passage can have linear protrusions such asare described in connection with FIGS. 1F1 through 113. Otherembodiments include further variations and combinations of linearprotrusions described in FIGS. 1F1 through 1I3. Still other embodimentsmay include curved linear protrusions, combinations of curved andstraight linear protrusions, and/or combinations of linear protrusionsand features such as bumps, indentations, etc.

The features described in connection with FIGS. 1A1-1I3 can be combinedin different manners and/or can be combined with other surface features,partitions, and/or other features inside the container. In general,increasing surface area for bubble nucleation will lead to more bubblesand adding obstructions will slow the rise of bubbles. In someembodiments in which a container is a bottle, the passage formed by apartition in FIGS. 1A-1I3 could be the passage of a bottle neck. Alength, inner volume and/or other features of the neck could be variedso as to affect bubble creation and/or movement.

Because the physical properties of bubbles like size, shape, quantityand rate of bubble release are interrelated, they can be tuned togetherby modifying a container configuration. Some or all of these propertiescan also be varied by configuring a container so as to change depth atwhich bubble nucleation occurs. The rise of the bubbles coming out ofthe container will depend on features in the passage through which thecarbonated liquid will exit the container. In some cases, beverageviscosity might be increased (e.g., by addition of sweetener syrup) ortiny particles can be suspended in (or designed to precipitate from) thebeverage so as to increase bubble stability. Particle precipitation canbe achieved by relying on decreased solubility of certain compoundsunder reduced pressure. Thus, such a compound might be fully dissolvedin a beverage when pressurized in a sealed container. Once the containeris opened, pressure is reduced and some of the compound wouldprecipitate from solution.

In some embodiments, when modifying pre-existing containers so as tocreate functional surfaces that affect bubble size, quantity and/orother properties, certain considerations are relevant. To achieveconsistency, it may be advantageous for as much of the beverage aspossible to contact the functional surface or be affected by thefunctional surface. To control cost, it may also be advantageous for afunctional surface to be consistent with current manufacturing processes(e.g., blow molding of polyethylene terephthalate (PET) preforms). It isalso desirable for the container (as modified) to be safe, e.g., topresent no choke hazards or toxic substances.

Some embodiments include beverage containers that improve flow dynamicsof a beverage through the neck portion of a bottle or other container.This improvement in flow dynamics can be achieved by reducing viscousdrag along the inner neck surface. The reduction in viscous drag canreduce the degree of “chugging” and the amount of gas released due todrag and turbulent flow. The end result can be improved flow andincreased bubbles remaining in the beverage. If drinking directly fromthe bottle, the result can be improved beverage flow into the mouth.There will also be an increase in the amount of bubbles remaining in thebeverage and thus, an improved mouth feel. The improved flow furtherreduces gas release in the mouth allowing for increased rate ofconsumption and an improved drinking experience.

In some embodiments these results are achieved through the use of“riblets,” a micro-geometry of longitudinal grooves and/or ridgesaligned with the direction of fluid flow. FIG. 2 shows one example of abottle 100 having a neck section 101 with riblets 102 formed around theentire inner circumference of neck 101. Bottle 100 has a side wall 182,a top 181 (of which neck 101 is a part) and a bottom (not shown). Bottle100 can be sealed at the outlet of neck 102 so as to contain acarbonated beverage in an interior volume of bottle 100, which outletcan then be opened to allow draining of the contained beverage from theinternal volume via the opened outlet.

In the embodiment of FIG. 2, the riblets extend the entire length ofneck 101, but this need not be the case in all embodiments. As shown inthe inset portion of FIG. 2, the riblets may be longitudinal groovesthat have approximately equal height-width dimensions. Variations inriblet dimensions can also be applied, however. Various patterns ofriblets and other features that also can be utilized are described,e.g., in U.S. Pat. Nos. 5,069,403 and 4,930,729, both of which arehereby incorporated by reference in their entirety. The cross-sectionalelevations of riblets (the peak to valley separation, which can be theheight of the riblet ridges and/or the depth of riblet grooves) can bein the range of 0.1 to 0.5 mm. Additional embodiments include ridgeshaving ranges of dimensions that include, without limitation, thosedescribed in U.S. Pat. Nos. 5,069,403 and 4,930,729. Other patterns thatcan be incorporated into containers according to one or more embodimentsinclude those described in U.S. Pat. Nos. 5,971,326 and 6,345,791, bothof which are also hereby incorporated by reference in their entirety.FIG. 3 shows a neck portion 201 of a bottle according to some otherembodiments, with the remainder of the bottle not shown. In theembodiment of FIG. 3, improved performance may be obtained by formingriblets 202 with a direction that is 45 degrees to a primary flowdirection 289 of the beverage flowing from the container interiorthrough an opened outlet in a top of the neck. In other embodiments,riblets in a neck or other container portion may be arranged atdifferent angles to a flow direction.

Riblets can be formed in any of various manners. For example,longitudinal ridges and/or grooves can be created by applying a negativepattern of the ridges and/or grooves to a surface of the portion of aninjection mold preform forming the inner neck surface. The body of acontainer can be tapered into the neck so as to form a shallow angle, asthe abruptness in this angle may encourage release of gas from abeverage being poured out of the bottle. Riblets can be tapered into thebody portion of a container and/or can extend the full length of thecontainer.

As indicated above, viscous drag can have undesirable effects relativeto the release of bubbles from a carbonated beverage. When a beverage isconsumed, particularly when consumed directly from a bottle or othercontainer, the container is tilted repeatedly such that the beverageflows back and forth across the inner surface of the container. Theviscous drag across the surface of the container causes release of gasfrom the beverage. The release of gas reduces the content of gas in thebeverage over time, and the beverage thereby becomes flat faster than itmight if the beverage container remained stationary.

Some embodiments address viscous drag over interior regions of abeverage container in addition to (or instead of) the neck portion. Atleast some such embodiments also use micro-geometry surface texture toreduce viscous drag at the container-beverage boundary layer. In oneembodiment, a beverage container has a dimpled interior surface suchthat the dimples form a concave surface at the beverage interface. Thisis shown in FIG. 4A. In FIG. 4A, a bottle 301 has a pattern of hexagonaldimples 302 over substantially all of the interior surface. Bottle 301has a side wall, a top (having a neck) and a bottom. Bottle 301 can besealed at the outlet of the neck so as to contain a carbonated beveragein an interior volume of bottle 301, which outlet can then be opened toallow draining of the contained beverage from the internal volume viathe opened outlet.

For convenience, only a portion of dimples 302 are shown. As shown inthe enlarged cross-sectional view of a lower portion of bottle 301, eachdimple 302 can have a concave inner surface 303 and a convex outersurface 304. FIG. 4B shows examples of additional dimple shapes andpatterns that can be used. The number of dimples can range from about80-160 (e.g., about 120) per square inch (per 6.45 square cm), althoughvarious other sizes and alternative configurations are possible.Examples of alternative dimensions include but are not limited to thosedescribed U.S. Pat. No. 5,167,552, which patent is hereby incorporatedby reference in its entirety. The depth of the dimples range may rangefrom about 0.1 to about 0.5 mm, e.g., about 0.1 to 0.15 mm, though otherdepths and/or ranges of depths can be used.

In additional embodiments, dimples similar to those indicated in FIGS.4A and 4B could be oriented in a reverse manner. In particular, dimplescould be configured such that the dimples have a convex inner surfaceand a concave outer surface. Dimples could be located throughoutsubstantially all of a container or in a single region of a container.For example, some embodiments can include a container in which dimplesare only located in a shoulder region, while other embodiments mightinclude a container in which dimples are only located in a girth region.In still other embodiments, dimples may be located in multiple discreteclusters of dimples, with a dimple cluster separated from anotherdimpled cluster by undimpled container wall material. Various clusterpatterns (e.g., a hexagonal soccer ball pattern) and/or combinations ofpatterns could be used.

Embodiments such as are shown in FIGS. 4A and 4B can be created usingblow mold techniques by including a pattern corresponding to the desireddimple pattern. If the pattern is formed from the outer surface of thecontainer contacting the blow mold, it may be useful to alter the sizeand/or detail of the pattern so as to accommodate some loss of finedetail and/or resolution on the interior surface of the moldedcontainer.

Additional embodiments use viscous drag reducing riblets on innersurfaces of a beverage container instead of (or in addition to) innersurfaces of a neck region. Such riblets can take the form of ribletsrunning the length of the container as shown in FIG. 5. Specifically,FIG. 5 shows one example embodiment of a bottle 401 having riblets 402that extend the length of the bottle interior. Bottle 401 has a sidewall, a top (having a neck) and a bottom. Bottle 401 can be sealed atthe outlet of the neck so as to contain a carbonated beverage in aninterior volume of bottle 401, which outlet can then be opened to allowdraining of the contained beverage from the internal volume via theopened outlet. For simplicity, only a portion of the riblets 402 areshown. FIGS. 6-11 show embodiments in which a pattern of riblets isformed on an interior container surface as a micro-geometry surfacetexture pattern. In the embodiments of each of FIGS. 6-11, the ribletscan be formed on a bottle or other container having a side wall, a top(having a neck) and a bottom. The bottle or other container can besealed at the outlet of the neck so as to contain a carbonated beveragein an interior volume of the container, which outlet can then be openedto allow draining of the contained beverage from the internal volume viathe opened outlet.

In the embodiments of FIGS. 6-11, the ridges (peaks) of some riblets maybe aligned with the grooves (troughs) of other riblets, effectivelyforming a micro-geometry surface texture pattern of a series ofdiscontinuous individual riblets. The patterns of FIGS. 6-11 may to adegree mimic the placoid scales of sharks. The micro-geometry of placoidscales reduces the viscous drag of a shark through water and allows ashark to swim with greater speed. The embodiments of FIGS. 5-11 may be“two-way”, i.e., they may reduce viscous drag in both longitudinaldirections such that the same effect is observed whether the beverage istilted down to pour or up to return the beverage to a stationaryposition in the container.

FIG. 6 shows an example of a bottle 501 having a pattern of riblets 502formed on the inner surface of the bottle. In the example of FIG. 6, theriblet pattern is a microgeometry pattern in which circumferential rowsof riblets are offset so that ridges of riblets in one row are alignedwith grooves of ridges in an adjacent row. Although only a portion ofthe riblet pattern is shown in FIG. 6, the pattern may extend over theentire inner surface of bottle 501.

FIG. 7 shows additional details of the pattern of riblets 502 of bottle501. As seen in the partial circumferential cross-sectional view, theriblets have a relatively sharp angular cross section. As seen in thepartial longitudinal profile view, riblet ridges on the interior ofbottle 501 are slightly bowed along their length. Also shown in FIG. 7is an alternative cross-sectional profile for another embodiment inwhich riblet ridges and grooves are more rounded.

FIGS. 8-11 shows additional examples of alternative riblet patterns.Although each of FIGS. 8-11 only shows a small section of examplepatterns, such patterns can extend over the entire inner surface of abottle or other container. FIG. 8 shows a pattern similar to that ofFIG. 7, but in which adjacent riblets have different lengths. The upperright corner of FIG. 8 shows a further modification in which the ribletridges and grooves are more rounded and/or in which some riblets haveheights that are larger than heights of adjacent riblets. FIG. 9 shows apattern of a group of riblets such as those of FIG. 8. FIG. 10 shows afurther variation on the riblet pattern of FIG. 7. In the pattern ofFIG. 10 there are at least three different lengths of riblets. FIG. 11shows a pattern of a group of riblets such as those of FIG. 10.

Ridge and groove patterns can have additional configurations in otherembodiments. The heights of ridges in embodiments of FIGS. 5-11 can bethe same as the example heights provided in connection with FIG. 2(e.g., approximately 0.1 to 0.5 mm). The lengths of ridges in theembodiments of FIGS. 5-11 may be in the range of about 0.5 to about 1.5mm, although other lengths can be used.

Embodiments such as are shown in FIGS. 5-11 can also be created usingblow mold techniques by including a pattern corresponding to the desiredriblet pattern. If the pattern is formed from the outer surface of thecontainer contacting the blow mold, it may be useful to alter the sizeand/or detail of the pattern so as to accommodate some loss of finedetail and/or resolution on the interior surface of the molded containerand so as to take account of the thickness of material between a moldand inner surface.

In some embodiments, a bottle, flask or other carbonated beveragecontainer has one or more bubble-forming structures formed on a bottomsurface or other surface. Because sharp edges can stimulate bubbleformation and act as nucleation sites, inclusion of such features in acontainer can promote formation of bubbles at a desired rate and of adesired size. FIGS. 12A1-12E2 are partially schematic drawings ofbeverage containers, according to at least some embodiments, having suchbubble-forming structures. Each of FIGS. 12A1-12E2 relates to one ofbottles 601 a-601 e, with each of bottles 601 having a side wall, a top(having a neck) and a bottom. Each of bottles 601 can be sealed at theoutlet of the neck so as to contain a carbonated beverage in an interiorvolume of the bottle, which outlet can then be opened to allow drainingof the contained beverage from the internal volume via the openedoutlet. For convenience, bottles 601 (and bottles in other drawingfigures) are shown with a flat bottom. However, bottles accordingvarious embodiments can include bottoms that are concave when viewedfrom an exterior, bottles with petaloid bottoms, and bottoms with othershapes.

Although FIGS. 12A1-12E2 show bottles as beverage containers, otherembodiments may include similar bubble-forming structures in other typesof containers. Moreover, other embodiments may include structuressimilar to those of FIGS. 12A1-12E2, but located at different positionson a container bottom and/or located at other positions within thecontainer (e.g., a side wall). Still other embodiments may includemultiple bubble forming structures of the types shown in one or more ofFIGS. 12A1-12E2 and/or combinations of different types of bubble formingstructures.

In the embodiments of FIGS. 12A1-12E2, bubble forming structures includespires or other structures having sharp points or edges. In some cases,two, three or more sharp points can be placed sufficiently close to oneanother such that bubbles form on each of the points and then join intolarger bubbles. This may permit control of bubble size by varying thenumber points and their relative distance from one another.

FIG. 12A1 shows a bottle 601 a according to one embodiment. FIG. 12A2 isan enlarged cross-sectional view of bottle 601 a taken from the locationindicated in FIG. 12A1. The bottom 602 a of bottle 601 a includes raisedportions 603 a and 606 a that terminate in sharp points 604 a and 605 a.In some embodiments, points 604 a and 605 a may instead be sharp edgesof a crater-like depression 607 a formed in a raised portion of bottom602 a.

FIG. 12B1 shows a bottle 601 b according to another embodiment. FIG.12B2 is an enlarged cross-sectional view of bottle 601 b taken from thelocation indicated in FIG. 12B2. The bottom 602 b of bottle 601 bincludes two raised portions 603 b and 606 b that terminate in sharppoints 604 b and 605 b. Unlike raised portions 603 b and 606 b of bottle601 b, however, raised portions 603 b and 606 b join bottom 602 b alongsharp corners 608 b and 609 b that can also promote bubble formation.Another sharp edge is in the bottom of depression 607 b. In someembodiments, peaks 604 b and 605 b may instead be sharp edges of acrater-like depression formed in a raised portion of bottom 602 b.

FIG. 12C1 shows a bottle 601 c according to another embodiment. FIG.12C2 is an enlarged cross-sectional view of bottle 601 c taken from thelocation indicated in FIG. 12C1. FIG. 12C3 is a further enlarged planview of the bottom 602 c of bottle 601 c taken from the locationindicated in FIG. 12C2. Bottle 601 c includes three spires 603 c-605 cformed on bottom 602 c. Spires 603 c-605 c can be solid and terminate inpoints, can be hollow (or partially hollow) and have sharpcircumferential edges at their tips, or may have other configurations.Although each of spires 603 c-605 c is of roughly the same height andshape, other embodiments include spires of differing heights and/ordiffering shapes. More than three spires can be included.

FIG. 12D1 shows a bottle 601 d according to another embodiment. FIG.12D2 is an enlarged cross-sectional view of bottle 601 d taken from thelocation indicated in FIG. 12D1. FIG. 12D3 is a further enlarged planview of the bottom 602 d of bottle 601 d taken from the locationindicated in FIG. 12D2. Bottle 601 d is similar to bottle 601 c, exceptthat the bottom 602 d of bottle 601 d includes three taller spires 603 dand nine shorter spires 604 d. Spires 603 d and spires 604 d can besolid and terminate in points, can be hollow (or partially hollow) andhave sharp circumferential edges at their tips, or may have otherconfigurations. Other embodiments may include additional (or fewer)spires, may include spires having heights different from those of spires603 d and 604 d, may include spires of differing shapes, may includedifferent combinations of spire height and shape, etc.

Spires such as those in FIGS. 12C1 through 12D3, as well as spires,raised portions, projections and/or other surface features according toother embodiments, can be scratched, sandblasted or otherwise abraded ortreated so as to create a roughened surface to increase nucleationsites. Spires, raised portions, projections and/or other surfacefeatures, whether or not roughened, can also be treated with siliconespray or another agent so as to modify the wetting characteristics of asurface and facilitate faster bubble release.

FIG. 12E1 shows a bottle 601 e according to another embodiment. FIG.12E2 is an enlarged cross-sectional view of bottle 601 e taken from thelocation shown in FIG. 12E1. Bottle 601 e includes a projection 603 eextending from bottom 602 e. Projection 603 e includes three sharppoints 604 e formed in an end of projection 603 e. Other embodiments mayinclude additional projections and/or projections with additional (orfewer) points.

The number, size, shape, distribution, and other aspects of spires,raised portions, projections and/or other surface features can vary innumerous ways in addition to those explicitly described herein.

Some embodiments include a bubble catching structure. FIG. 13A1 shows abottle 701 a according to one such embodiment. FIG. 13A2 is an enlargedcross-sectional view of bottle 701 a taken from the location shown inFIG. 13A1. Each of FIGS. 13A1-13C2 relates to one of bottles 701 a-701c, with each of bottles 701 having a side wall, a top (having a neck)and a bottom. Each of bottles 701 can be sealed at the outlet of theneck so as to contain a carbonated beverage in an interior volume of thebottle, which outlet can then be opened to allow draining of thecontained beverage from the internal volume via the opened outlet.Bottle 701 a includes dome-shaped bubble catching structure 703 aanchored to the bottom 702 a. For convenience, tabs or other structuresconnecting bubble catching structure 703 a to bottom 702 a are notshown. Bubble catching structure 703 a forms a volume 704 a that ispartially separated from the main volume 707 a. Except for regionsaround the edges of bubble catching structure 703 a and an orifice 705 ain bubble catching structure 703 a, liquid (and bubbles) cannot passbetween regions 704 a and 707 a. As also shown in FIG. 13A2, orifice 705a is located at or near the highest portion of the dome of bubblecatching structure 703 a. When bottle 701 a is in an uprightconfiguration, bubbles trapped under structure 703 a can only escapeinto main volume 707 a through orifice 705 a, but liquid in bottle 701 acan readily reach region 704 a through the openings at the edges ofstructure 703 a.

The upper surface 708 a of structure 703 a is smooth so as to minimizebubble formation. However, the underside 706 a of structure 703 a and/orbottom 702 a contain numerous scratches, sharp edges, etc. to stimulatebubble formation. Bubbles forming under structure 703 a will join intolarger bubbles prior to (or during) escape through orifice 705 a toregion 707 a.

FIG. 13B1 shows a bottle 701 b according to another embodiment. FIG.13B2 is an enlarged cross-sectional view of bottle 701 b taken from thelocation shown in FIG. 13B1. Bottle 701 b is similar to bottle 701 a,except that dome-shaped bubble catching structure 703 b is not fixed tobottom 702 b. Instead, structure 703 b can move up and down withinvolume 707 b. Thus, region 704 b is not of fixed size. The upper surface708 b is smooth. Bottom surface 706 b (and/or bottom 702 b) includesscratches, sharp edges and/or other surface features to promote bubbleformation. Bubbles formed under structure 703 b gather and escapethrough orifice 705 b, with orifice 705 b located at or near the highestportion of the dome of bubble catching structure 703 b. In someembodiments, formation of sufficiently large bubbles under structure 703b may permit structure 703 b to move up and down within main volume 707b in a periodic manner. In some embodiments, structure 703 b may bestabilized by lowering its center of gravity (e.g., attaching a weightto the underside) and/or by making the sides of structure 703 b fitrelatively close to the inside walls of bottle 701 b. In the embodimentsof FIGS. 13A1-13B2, the size of bubbles entering the main volume of thebottle can be controlled based on the diameter of the orifice.

FIG. 13C1 shows a bottle 701 c according to another embodiment. FIG.13C2 is an enlarged cross-sectional view of bottle 701 c taken from thelocation shown in FIG. 13C1. Bottle 701 c includes a structure 703 cthat is able to move freely within main volume 707 c. One or both facesof structure 703 c can have scratches, sharp edges and/or other surfacefeatures to promote bubble growth. Structure 703 c lacks an orifice andis permitted to rotate freely. Bubbles formed on the underside ofstructure 703 c escape upwards when structure 703 c is tilted upward.Structure 703 c can be symmetric or non-symmetric, can have the shapeshown, or can have other shapes. In some embodiments, structure 703 chas a width (W_(w)) that is greater that the width (A) of the neckopening of bottle 701 c and a length (L_(w)) that is less than a width(B) of the bottle 701 c interior. More than one structure 703 c could beincluded in bottle 701 c.

Although FIGS. 13A1-13C2 show embodiments in which the beveragecontainer is a bottle, structures such as are shown in FIGS. 13A1-13C2can be used in other embodiments where a container is a can, a reusableor disposable cup, etc.

In some embodiments, a beverage container shape can be configured so asto increase internal surface area and/or to increase the number ofinternal corners, edges or other surface features that may help promotenucleation. For example, a container could be formed with a throughhole, an indentation, a notch, etc. Examples of such bottles are shownin FIGS. 14A1-14D. Each of the bottles in FIGS. 14A1-14D includes sidewalls, a top (having a neck) and a bottom. Each of those bottles can besealed at the outlet of the neck so as to contain a carbonated beveragein an interior volume of the bottle, which outlet can then be opened toallow draining of the contained beverage from the internal volume viathe opened outlet. As an additional advantage, container configurationssuch as are shown in FIGS. 14A1-14D can also be used to createdistinctive appearances for product marketing or other purposes. FIG.14A1 shows a bottle 800 having two sealed through-holes 801 and 802formed therein. FIG. 14A2 is a cross-sectional view of bottle 800 fromthe location indicated in FIG. 14A1. As seen in FIG. 14A2, each of holes801 and 802 provides an external passage through the body of bottle 800without exposing the bottle interior. FIG. 14B shows a bottle 810 havinga star-shaped sealed through hole 811. FIG. 14C is a lengthwisecross-sectional view of a bottle 815 having multiple notches 816 thatproject inward to the bottle interior. FIG. 14D is a lengthwisecross-sectional view of a bottle 825 having a pair of notches thatproject inward. Protrusions 827 extend from the interior surfaces ofnotches 826. In still other embodiments, the entire outer profile of thebottle could be custom shaped (e.g., a long serpentine shape, a starshape) so as to increase internal surface area and/or internalnucleation features.

Beverage containers according to various embodiments can be formed usingany of various techniques. For example, nucleation sites can be formedon interior regions of a plastic beverage bottle during a blow moldingprocess. As indicated above, a mold used to form a plastic bottle caninclude protrusions, recesses or other features that create externalfeatures on the bottle outer surface. These external features will thenhave corresponding features on internal surfaces of the bottle (e.g.,creating a dent in the bottle exterior will create a bump in the bottleinterior).

As another example, internal surface features can be formed on a plasticbottle preform using a core rod having surface features corresponding tothe desired surface features. Upon stretching and blowing of thepreform, the internal surface features of the preform will becomeinternal surface features of the plastic bottle. FIG. 15A is a frontview of a core rod 901 according to one embodiment. FIG. 15B is across-sectional view of the front end of core rod 901 from the locationindicated in FIG. 15A. Rod 901 includes numerous ultra fine channels 902formed in the curved front face 903 of rod 901. In operation, core rod901 is placed into a mold chamber. Molten PTE or other material is theninjected into the space between rod 901 and the chamber walls so as tocreate a preform that can later be used to blow mold a beveragecontainer. During the injection molding process, molten material flowsinto the channels 901 to create pointed protrusions on a portion of thepreform that will correspond to the interior bottom surface of theresulting plastic bottle. The sizes (diameter and/or depth) of eachchannel 902 can be varied in different embodiments, and all channelsneed not have the same dimensions. The number and distribution ofchannels can likewise be varied in other embodiments. In someembodiments, one or more channels at the frontmost tip of end 903 may beomitted so that the resulting preform will have a region withoutprotrusions so as to better accommodate a stretch rod during the blowmolding process. In still other embodiments, a push rod used with apreform created with core rod 901 may have a concave cup-like end thatfits over projections in the preform. The concave region of that endaccommodates the projections without damaging them during the stretchblow molding process. A ring of the push rod end pushes against aportion of the preform surface surrounding the protrusions in thepreform.

FIG. 17A is a picture showing a cross section of a preform created witha core rod similar to core rod 901 of FIGS. 15A and 15B. However, thecore rod used to create the preform of FIG. 17A only has nine channels.Those channels are wider than channels 902 of core rod 901 and areconically shaped. FIG. 17B is a picture of the interior bottom of abottle stretch blow molded from the preform of FIG. 17A.

Internal surface features in a container can alternatively (or also) becreated by modifying a stretch rod used to push against the bottomsurface of a preform during blow molding. Such a stretch rod can be usedto impart spikes or other projections, asperities, inclusions or othertypes of surface features on an interior base region of a blow moldedbottle. A stretch rod could alternatively, or additionally, be used toimpart a surface texture to a bottle interior base region. In additionto forming nucleation sites for use in control of bubble formation,textures and surface features formed on a bottle interior or exteriorcan be used to incorporate decorative features for aesthetic purposes.

FIG. 15C is a block diagram of steps in forming a plastic bottle havingone or more internal surface features using a stretch rod having amodified tip. In step 991, a stretch rod having the modified tip isinserted into a plastic preform that has been sufficiently heated. Theneck portion of the preform is secured relative to an axis of motion ofthe stretch rod (i.e., an axis that will also correspond to thelongitudinal axis of the bottle to be formed). In step 992, the stretchrod is pushed against an inner bottom surface of the preform so as toforce heated plastic of the preform into the cavities in the modifiedtip. In step 993, a gas (e.g., air) is blown into the stretched preformand the preform is expanded axially against the inner walls of the blowmold. This results in a bottle having bottom surface features thatcorrespond to the surface features in the stretch rod tip. Differenttypes of rod tips can be used to form various types of interior surfacefeatures in a blow molded container.

For example, FIG. 16 is a picture showing the ends of four stretch rods921-924 according to some embodiments. Rod 921 has seven conicaldepressions 929 formed in its end face 925. Each of depressions 929 isapproximately 0.05 inches deep. Rod 922 has seven conical depressions930 formed in its end face 926. Each of depressions 930 is approximately0.1 inches deep. Rods 923 and 924 have a plurality of irregularly shapeddepressions formed in their respective end faces 927 and 928.

Test bottles were blown with each of the end rods shown in FIG. 16 usinggreen plastic preforms. Processing adjustments were made to slow themolding machine so as allow temperature to equilibrate more thoroughlyinside of the preforms, and to thus allow details to form more fully.The stretch rods were also adjusted to pin the preform material moretightly than in conventional blow molding so as to press preformmaterial into the bottoms of the stretch rods. A flat surface in thebase mold corresponding to the location against which the rod endpresses is desirable.

FIG. 17C is a picture of an inside of a bottle blow molded with rod 921.In some cases, it may be easier to create high aspect ratio protrusions(such as are shown in FIG. 17B) using a modified core rod (such asdescribed in connection with FIG. 17A) instead of a modified push rodsimilar to push rod 922.

All features of the bottles blow molded with rods 921-924 acted asnucleation sites. The rate of bubble release was controlled inaccordance with bubble growth rates attributable to the respectivesurface features. FIGS. 17D and 17E show nucleation resulting fromsurface features similar to those shown in FIG. 17C.

In other embodiments, nucleation sites can be formed in other manners.FIG. 18 is a cross-sectional view of a portion of a bottle 1001according to one such embodiment. Bottle 1001 includes a bottom 1003 anda side wall 1002 (only a portion of which is shown), as well as a top(not shown) having a neck (also not shown). Bottle 1001 can be sealed atthe outlet of the neck so as to contain a carbonated beverage in aninterior volume of bottle 1001, which outlet can then be opened to allowdraining of the contained beverage from the internal volume via theopened outlet.

Bottom 1003, side wall 1002 and the top of bottle 1001 are formed from afirst material (e.g., PET or other plastic). Embedded in the interiorsurface of bottom 1003 and/or a lower portion of side wall 1002 aremultiple discrete elements 1004. Elements 1004 are partially exposed toa beverage contained in bottle 1001. Although not shown in thecross-sectional view of FIG. 18, elements 1004 may distributed acrossthe entire surface of bottom 1003 and around the entire circumference ofbottle 1001 in the lower portion of side wall 1002. Each of elements1004 is formed from a second material that can be different from thefirst material. For example, discrete elements 1004 can include embeddedparticles (e.g., sand-sized) of silica, of an inorganic material, of aplastic different from the first material plastic, of an inorganicmaterial, etc. Other materials that can be embedded in or otherwiseattached to a bottle interior surface, or otherwise placed into a bottleinterior, can include wood fibers adhered to a bottle base, coffeefilter material, food grade insoluble fibers, cellulose/PET fibersoptimized for wicking characteristics and bubble texture control,fibrous meshes having air bubbles trapped therein to act as CO₂ bubblenucleation sites, semi-permeable membranes floating on a beveragesurface and having pores size slightly smaller than the moleculardimension of O₂, and activated charcoal inclusions.

In some embodiments, side wall surface portions having embedded elements1004 may extend further upward in the bottle (e.g., approximately halfof the bottle height). In still further embodiments, only the interiorbottom surface may have embedded elements. In yet other embodiments,only interior side wall surfaces may have embedded elements. Embeddedelements can be arranged in multiple groupings separated by regionswithout embedded elements.

In still other embodiments, a bottom or other interior surface can beroughened by sand blasting, by cryogenic abrasion, etc. In still otherembodiments, known techniques for creating a bottle with a foamedplastic layer can be modified to create a bottle with one or more foamedplastic regions in the bottle interior. Techniques for creating bottleswith a foamed plastic layer are described, e.g., in U.S. Pat. No.7,588,810, in U.S. Pat. App. Pub. No. 20050181161, in U.S. Pat. App.Pub. No. 20070218231, in U.S. Pat. App. Pub. No. 20080251487, in U.S.Pat. App. Pub. No. 20090297748, and in International Pat. App. Pub. No.WO 2008/112024; each of these documents is incorporated by referenceherein in its entirety.

With regard to beverage containers formed by any of various methods,various factors can be considered when attempting to increaseeffervescence. In general, a larger number of nucleation sites resultsin more bubble formation. With regard to geometry of nucleation sites, ahigh surface energy is desirable. This typically corresponds to a highaspect ratio (i.e., a large height:width ratio). Tall and slimstructures (e.g., oblate similar to orzo pasta, needles) can be usefulin this regard. The density of nucleation sites in a given area is alsorelevant. Larger bubbles may form from regions with increased nucleationsite density, and larger bubbles may release and rise more quickly. Thelocation of nucleation sites may also be relevant. It may sometimes beuseful to place nucleation sites at the bottom of a container becausepotential energy associated with surface tension may be higher at thebottom base than in the bottle neck.

A larger number of spikes (or other type of projections) can cause morebubble release than fewer spikes (or other type of projections). Largerspacing between spikes/projections can also increase the number ofbubbles released and/or decrease the sizes of released bubbles. Theinverse relationship with spacing and number of spikes/projections alsoholds true.

EXAMPLE 1

The pressure inside of a bubble is represented by Equation 1:P _(bubble) =P _(atm) +P _(carbonated liquid)+2Y/R  (Eq. 1)

where:

-   -   Y=surface tension of carbonated liquid    -   R=radius of pore    -   P_(carbonated liquid)=pressure exerted by the liquid above the        bubble    -   P_(atm)=atmospheric pressure

FIG. 19 shows the variation in size and pressure of a bubble risinginside a liquid. As can be deduced from Eq. 1, the equilibrium pressureinside the bubble is inversely proportional to the bubble size. Thepressure inside the bubble is also dependent upon the surface tension ofthe carbonated liquid. As the bubble rises, the pressureP_(carbonated liquid) decreases. Because the equilibrium pressure insidethe bubble is dependent upon the pressure exerted by the carbonatedliquid above the bubble, P_(bubble) also decreases accordingly. Thisdecrease in pressure is accommodated by an increase in the size of thebubble. In addition to this, with the rise of bubbles, the gas from thecarbonated liquid surrounding the bubble also diffuses into the bubblebecause of pressure differences. What follows is a mathematicalexplanation of why extremely minute bubbles will not form without somesurface bubble nucleation.

The shape of the bubble will tend towards spherical as thesurface/volume ratio is lowest for this shape. But the bubble inside aliquid has to push the surrounding liquid while rising and therefore, inreality, has a shape that is slightly distorted. For the sake ofsimplicity in calculation, however, the shape is assumed to bespherical. Is further assumed that the bubble radius is R, surfacetension of the liquid is Y, gas density is ρ, and F is free energyrelease achieved when 1 gram of gas is transferred from supersaturatedsolution into the bubble. The surface of the bubble will be 4ΠR². Inorder to create this much surface inside the liquid, the work to be doneagainst the surface tension of the liquid is equal to 4ΠR²Y. The amountof gas in the bubble will be (4/3)ΠR³ρ. The free energy release for onebubble would be (4/3)ΠR³ρF. Spontaneous gas evolution is possible onlyas long as 4/3ΠR³ρF>4ΠR²Y, i.e., as long as RρF>3Y. It is clear from thethis relationship that, whatever (within interest) the values of ρ, Fand Y, the term RρF would be less than 3Y for sufficiently small valuesof R. And, as bubbles must be minute at the time of nucleation beforethey grow, extremely minute bubbles can not form simultaneously.

Assuming that supersaturated carbonated liquid would be in equilibriumwith gas under a pressure P, it would tend to diffuse gas to a spacewhere pressure is less than P. In a random nucleation event, there is astatistical chance that small and large (R) bubbles occursimultaneously, but they may not be sustained. It is the Gibbs Freeenergy balance of volume and surface area energies that will dictatewhether these nuclei are thermodynamically stable enough to grow. Abovea critical free energy, the nuclei can grow. From Eq. 1, it is evidentthat the pressure in bubble is greater than the surrounding liquid by2Y/R (assuming pressure exerted by the carbonated liquid is negligible).Thus a bubble will grow only if the term 2Y/R is less than thesurrounding pressure P. As at the time of nucleation, R has to besufficiently small, the above condition can be satisfied by improbablygreat values of P only. Providing readily available surface for thenucleation of bubbles inside a carbonated liquid for a given volume ofcontainer can facilitate foaming.

CONCLUSION

The foregoing description of embodiments has been presented for purposesof illustration and description. The foregoing description is notintended to be exhaustive or to limit embodiments to the precise formexplicitly described or mentioned herein. Modifications and variationsare possible in light of the above teachings or may be acquired frompractice of various embodiments. The embodiments discussed herein werechosen and described in order to explain the principles and the natureof various embodiments and their practical application to enable oneskilled in the art to make and use these and other embodiments withvarious modifications as are suited to the particular use contemplated.Any and all permutations of features from above-described embodimentsare the within the scope of the invention.

The invention claimed is:
 1. A method, comprising: placing a core rodinto a mold chamber, wherein the core rod has numerous channels formedin a front face of the core rod; injecting molten plastic into a spacebetween the core rod and walls of the mold chamber so as to create apreform having pointed protrusions; and blow-molding the preform so asto create a plastic bottle having the pointed protrusions on an interiorbottom surface of the plastic bottle; wherein the blow-molding comprisesstretch blow molding with a push rod having a concave cup-like end thatfits over the pointed protrusions in the preform.
 2. The method of claim1, wherein not all of the channels have the same dimensions.
 3. Themethod of claim 1, wherein a ring of the push rod end pushes against, aportion of the preform surface surrounding the pointed protrusions inthe preform.
 4. The method of claim 1, wherein the channels areconically shaped.
 5. The method of claim 1, wherein the pointedprotrusions are conically shaped.
 6. The method of claim 1, wherein themolten plastic comprises molten polyethylene terephthalate (PET).